DHCP Roaming Issue

We have an external DHCP server, using a client connecting to a AP via IEEE802.1X, It moves to another access point it starts a DHCP Request for a new address, It gets the same address as before but it drops the TELNET connection, but with fixed addresses, it maintains the connection to TELNET across the AEROHIVE Network of AP's

Can you tell myself why? And how to use DHCP rather than using fix's addresses?